Color developers containing aromatic primary amine developing agents have long been used for forming colored images, and they have played a central role in the formation of the colored images in color photographs. However, the above-mentioned color developers are very easily oxidized by air and metals. It is known that increased fogging and changes in sensitivity and gradation occur when a colored image is formed with an oxidized developer and it is impossible to achieve the desired photographic characteristics.
Hence, various means of increasing the preservation properties of color developers have been investigated in the past. Among these methods, a method in which hydroxylamine and sulfite ion are used in combination is most generally used. However, ammonia is formed when hydroxylamine breaks down and this causes fogging, and the sulfite ion acts competitively with the main developing agent and has the disadvantage of inhibiting color formation. Therefore, neither of these compounds can be said to be good preservatives.
Various other preservatives and chelating agents have been investigated in the past in an attempt to increase the stability of color developers. For example, the aromatic polyhydroxy compounds disclosed in JP-A-52-49828 (the term "JP-A" as used herein refers to a "published unexamined Japanese patent application"), JP-A-59-160142, JP-A-56-47038, and U.S. Pat. No. 3,746,544, the hydroxycarbonyl compounds disclosed in U.S. Pat. No. 3,615,503 and British Patent 1,306,176, the .alpha.-aminocarbonyl compounds disclosed in JP-A-52-143020 and JP-A53-89425, the alkanolamines disclosed in JP-A-54-3532 and the metal salts disclosed in JP-A-57-44148 and JP-A-5753749, etc., have been suggested as preservatives. Furthermore, the aminocarboxylic acids disclosed in JP-B48-30496 (the term "JP-B" as used herein refers to an "examined Japanese patent publication") and JP-B-4430232, the organic phosphonic acids disclosed in JP-A-5697347, JP-B-56-39359 and West German Patent 2,227,639, the phosphonocarboxylic acids disclosed in JP-A-52102726, JP-A-53-42730, JP-A-54-121127, JP-A-55-126241 and JP-A-55-65956, and the other compounds disclosed in JP-A58-195845, JP-A-58-203440 and JP-B-53-40900, etc., have proposed as chelating agents.
However, adequate preservation capacity cannot always be achieved using these techniques. Accordingly, there may be adverse effects on the photographic characteristics, and satisfactory results will not be obtained.
A deterioration in color forming properties is inevitable with color developers from which benzyl alcohol, a compound which is harmful in terms of pollution and preparation of solution, has been excluded. In such a system, the preservatives which act as competitive compounds inhibit color formation. Many of the techniques investigated in the past have proved unsatisfactory.
Moreover, color photographic materials which contain silver chlorobromide emulsions which have a high chlorine content are prone to fogging during color development, as described in JP-A-58-95345 and JP-A-59232342. Dissolution of the emulsion is slight in cases where emulsions of this type are used and preservatives which have a superior preserving capacity are essential. In this sense, no satisfactory preservative has yet been discovered.